Rotational Molding worked example

Cooling Cycle Time at 7.2% cooling time safety allowance: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop cooling time safety allowance to 7.2%, then walk the calculation through step by step. Cooling cycle time is how long a rotomolded part stays under forced air or water spray after the oven so the melt solidifies and sets its final shape while the mold keeps rotating.

The inputs for this scenario

  • Total heat to remove from part: 120 BTU-equivalent units (held at the documented default)
  • Cooling heat removal rate: 12 units / hr (held at the documented default)
  • Cooling time safety allowance: 7.2 % (the input this scenario stresses; the baseline uses 10)

Working through the calculation

  • The calculation starts from the formula this tool documents: Base cooling cycle time time = required work รท processing rate.
  • Adjusted run time works out to 10.72 hr at these inputs, and this is the headline figure for the scenario.
  • Base run time works out to 10 hr at these inputs.
  • Allowance applied works out to 7.2 % at these inputs.
  • Process rate works out to 12 pieces / min at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where cooling time safety allowance sits at 10% and the headline result is 11 hr, this scenario comes in 2.55% below the baseline at 10.72 hr.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to cooling time safety allowance, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It assumes a steady cooling rate; real cooling is nonlinear and depends on air/water flow, mold material, and part geometry, so validate demold flatness and dimensions.

Results at a glance

  • Adjusted run time: 10.72 hr (headline result)
  • Base run time: 10 hr
  • Allowance applied: 7.2 %
  • Process rate: 12 pieces / min

Run it with your numbers

  • To rerun this with your own numbers, open the live Cooling Cycle Time calculator, set cooling time safety allowance to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.